Ultimate Suite for PowerBuilder includes icon libraries that you can use in your PB applications*.

 
Silk Icons

V 1.3

Author: Mark James

Creative Commons Attribution 2.5 License

PBUS Sample App Icons

2018

Author: Novalys

Creative Commons Attribution 2.5 License

 
NuoveXT

v. 2.2

Author: Alexandre Moore

Lesser General Public License (LGPL)

*in accordance with their license agreement